Minecraft – Will a dragon head drop if you kill the dragon with a charged creeper

Assuming you're on creative with cheats enabled and on version 1.7, you should be able to place down a command block and insert this command into it:

/setblock ~ ~ ~ mob_spawner 0 replace {EntityId:Creeper,SpawnData:{powered:1}}

Then power with any redstone device, and the command block should turn into a charged creeper spawner.

Here are some options and some considerations:

• You can build in the end while the Dragon is still alive as long as you build far enough from the main island.
• Alternatively, you can lead the dragon far away from the main island and store the dragon in unloaded chunks. Then you can build at the main island at will. Just make sure no one walks in the direction of the dragon, because it will be loaded again and it will escape (it'll make its way back to the main island).
• Putting your base at The End without killing the dragon is not very practical, because you have to kill yourself to go back.
• You can actually trap a dying dragon with pistons that constantly move (on a clock). It is very hard to do that for alive dragon, though (especially in survival).
• Here is a very cool video showing how to build a dragon XP farm. It also shows how to temporary store the dragon in far-away chunks, and the 'trap with pistons' trick: